Cu-doped TiO2 nanoparticles/graphene composites for efficient visible-light photocatalysis

Cu-doped TiO2/graphene (Cu–TiO2/GR) composites were successfully synthesized by a simple hydrothermal method. The coating of anatase TiO2 nanoparticles on the whole graphene was confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). UV–visible diffuse reflectance spectroscopy (DRS) showed that the resulting Cu–TiO2/GR composites exhibited extended light absorption in visible-light region compared with pure TiO2. Photoluminescence emission spectra of Cu–TiO2/GR composites showed better charge separation capability as compared to Cu/TiO2 and pure TiO2. The photocatalytic activity was evaluated by degradation of methyl orange (MO) dye under visible-light irradiation. The results demonstrate that Cu–TiO2/GR composite can effectively photodegrade MO, and show an excellent photocatalytic enhancement over pure TiO2. It was concluded that the synergistic effects of the great adsorptivity of dyes, extended light absorption range and efficient charge separation played a significant role for the enhancement of photoactivity of Cu–TiO2/GR composite catalyst.